The objective of this study is to gain a better understanding of the ultrastructural details of gonadotrophic hormone secretion. Immunocytochemical procedures are being developed and utilized for the visualization of the anterior pituitary hormones, FSH and LH. This will enable one to examine the processes on intracellular hormone synthesis and transport and to determine the mechanisms of hormone excretion. Effects of natural and synthetic LH/FSH-RH on the secretion of FSH and LH are being investigated in a number of animal preparations. Hypophysectomized rats bearing pituitary grafts under the renal capsule are being treated with TRH as well as LH/FSH-RH in order to determine the specificity of action of these hypothalamic hormones. Current work involves the use of antibodies to subunits of FSH and LH in attempts to localize these hormones at both light and electron microscopic levels. The influence of the pineal gland on gonadotrophic hormone secretion is also under investigation.